This invention relates to a signal processing apparatus having a movement detecting means and an outline enhancing means.
Recently, with the progress in the technique of producing solid state imaging devices, images are high in density, chips are very small and an endoscope fitted with a solid state imaging device in the tip part or a so-called electronic endoscope apparatus is developed. Such an apparatus has a function of observing an inspected part and recording the observed image of the part when the apparatus is inserted into a body cavity. Not only the inspecting activity but also the quality of the recorded image is so important as to greatly influence the diagnosis of the inspected part. Therefore, in recording, the endoscope operator has stilled the patient, has frozen and displayed the image of the inspected part several times, has selected the most desirable image as a recorded image and has recorded the still picture, for example, in a monitor image photographing apparatus, video printer or still video floppy apparatus.
However, even if the patient is stilled, so long as the living body interior is observed, the inspected part will move a little and, in order to eliminate the movement of the image due to this movement, the image will have to be re-frozen several times in some case.
In order to cope with this problem, a movement detecting circuit shown in FIG. 1 is devised. Embodiments of an endoscope using this movement detecting circuit are shown in FIGS. 2 and 3. FIG. 2 is of an endoscope apparatus removably connected with a movement detecting apparatus as a peripheral instrument. FIG. 3 is of an endoscope apparatus having a detecting circuit built-in. In FIG. 2, an endoscope apparatus 1 comprises an electronic endoscope 2 to be inserted into a body cavity, a controlling apparatus 5 having a signal processing part, a light source apparatus 3 feeding an illuminating light to the above mentioned electronic endoscope 2, a monitor 4 displaying an object image and a movement detecting apparatus 6. The above mentioned electronic endoscope 2 has an insertable part 7 to be inserted into a body cavity. An objective lens system 9 and an emitting end surface of a light guide 11 emitting the illuminating light are provided on the tip surface of this insertable part 7. The light guide 11 is inserted through the insertable part 7 and is connected to the above mentioned light source apparatus 3. The illuminating light emitted by a light source lamp 12, transmitted through a rotary filter 15 rotated by a motor 13 and condensed by a condenser lens 14 enters the connected light guide 11 on the entrance end surface. This illuminating light is radiated to an object 10 from the exit end surface of the light guide 11. The illuminated object 10 forms an image on the imaging surface of a solid state imaging device 8 by the above mentioned objective lens system 9. This formed image is photoelectrically converted, is read out by a CCD driver 29 and is delivered as an electric signal to the controlling apparatus 5. This electric signal is written into an R memory 19R, G memory 19G and B memory 19B by a multiplexer 18 through a tone correcting circuit 16 and A/D converter 17. The written video data are read out and are outline enhanced in an R outline enhancing circuit 21R, G outline enhancing circuit 21G and B outline enhancing circuit 21B and are delivered to the above mentioned movement detecting apparatus 6 through D/A converters 20a, 20b and 20c.
In FIG. 4, the video data from the respective memories 19 are delayed by a delaying device d1 and are input into an adder Al. The output of this delaying device d1 is further input into a delaying device d2 and is input into adders A2 and A3. The output of the delaying device d2 is added in the adder Al and the output of this adder A1 is multiplied by -1/2 in a counter C1, is input into the above mentioned adder A2 and is made an outline enhancing component. This outline enhancing component is multiplied by .alpha. in the counter C2 and has a signal level set. The output of this counter C2 is added to the output of the above mentioned delaying device d1 in the above mentioned adder A3 to obtain video data which is outline enhanced.
In the above mentioned movement detecting apparatus 6, when a freezing signal is input from a switch (not illustrated) or the like, the image of the least movement of the input images will be detected, a freezing signal will be output to the respective memories 19 (representing 19R, 19G and 19B) at the timing at which this image has been detected and it will be inhibited to write the video data into the memories 19. The memories 19 repeatedly read out the video data to display the still image of the least movement in the monitor 4.
In FIG. 3, the same as in FIG. 2, video data is input into a movement detecting circuit 22 from the respective outline enhancing circuits 21 (representing 21R, 21G and 21B) and the image of the least movement is detected. The video data having had the movement quantities detected are converted to a composite video signal, for example, of an NTSC system by an encoder 30 through the D/A converters 20 (representing 20a, 20b and 20c).
Here, it is assumed that, in FIG. 2, in case the outline enhancing circuit 21 is off, the video signals R, G and B at the output terminal 23 of the controlling apparatus 5 shall be such signals as are shown in FIGS. 5(a), 5(b), 5(c) (wherein the R signal frequency component shall be higher than the G and B signal frequency components and no color movement of R, G and B shall be produced).
In case the movement is detected on these signals R, G and B, the signals will be sampled in each predetermined sampling period by coding means 24a, 24b and 24c forming the movement detecting circuit 22 shown in FIG. 1, the correlation will be detected by a comparing means 26 and further the movement quantity will be detected by a quantifying means 25. A visible model of the correlation detection is shown in FIG. 6.
In FIG. 6, the signals R, G and B shown respectively in (a), (b) and (c) are sampled for the periods of the mark .circle. by the coding means 24a, 24b and 24c and the variations .DELTA.R, .DELTA.G and .DELTA.B of level in this sampling period are shown by signs (+, - and 0) as in (d) in FIG. 6. For these signs, exclusive logical sums (exclusive OR) FL1 and FL2 are taken in a comparing means 68 and further a logical sum (OR) FLAG of FL1 and FL2 is taken. In FIG. 6, FLAG does not stand at all and no color movement is detected to be produced.
On the other hand, in case the outline enhancing circuit 21 is on for the above mentioned object, such correlation detection as is shown in the visible model in FIG. 7 will be made the same as is mentioned above on the video signals R', G' and B' output from the output terminal 23 and enhanced in the outline. In FIG. 7, though the signals shown in FIG. 5 the same as in the case that the outline enhancing circuit 21 is off are input, four FLAG's stand and the color movement quantity is detected to be large.
Next, in FIG. 8, in a visible model shown for the images in which there is a color movement by a time .tau. in only the R image, three FLAG's stand. Though there is a color movement as compared with the number of FLAG's in FIG. 7, the sensed color movement quantity is small and the color movement sensing precision is low.
The circuit in case the enhancing fequency is switched in the outline enhancing circuit 21 in FIG. 4 is shown in FIG. 9. In an outline enhancing frequency switching circuit 28 in FIG. 9, the enhancing frequency can be varied by switching such tap of DL36 as is shown in FIG. 10 by a controlling signal from an external enhancing frequency band setting input. The images of R, G and B in case the enhancing frequencies which are switched are a MH.sub.z and b MH.sub.z are shown in FIGS. 12 and 13, (the output images of the endoscope apparatus are shown in FIG. 14) and the visible models for the respective images show that, in the case of a MH.sub.2 (FIG. 12), five FLAG's will stand and, in the case of b MH.sub.z (FIG. 13), the FLAG's will be three and the sensed color movement quantity will be smaller than in a MH.sub.z. Therefore, when the enhancing frequency is varied, the color movement sensing precision will vary to be a great trouble.
Also, in case the endoscope appartus 1 is provided with such tone correcting circuit 27 as is shown in FIG. 15 so that the levels of the signals R and B for the signal G may be variable with the intention of the user, if there is a random noise 27a uniformly, for example, in the images R, G and B, the level of the signal R will be elevated by the tone correcting circuit 27. As the outline of this image is enhanced, the output will be as shown in FIG. 16. In such a case, the number of FLAG's will be 8 and therefor color movement as is shown in FIG. 17 will be produced but, for the image having no random noise, the number of FLAG's will be 5, the sensed color movement quantity will be reduced and the color movement sensing precision will vary.
The tone correcting circuit 27 in FIG. 15 switches on and off the respective switches within SW1 and SW2 by the controlling information from the external tone setting switch, selects the respective resistances R of the base earthing circuit and varies the respective gains of R and B for G to correct the tone.
In case the movement detecting circuit 22 (or the movement detecting apparatus 6) is provided in the step after the outline enhancing circuit, the precision of sensing the color movement and image movement will reduce and the image having a color movement or image movement will be likely to be mis-sensed to be an image having no color movement or image movement.